The present invention relates to a telephone message recording device, hereinafter frequently referred to as a answering device comprising recording means for recording of calls and incoming messages.
In a known telephone answering device as described in the U.S. Pat. No. 3,937,893, in practice display means are provided which show the operating state of the answering device. One of these display means, formed by a light source of predetermined colour, indicates whether a call has been received. The user of the telephone answering device then has the possibility of listening to the recording memory means to hear the identity of the caller and the message left by him. However, in many cases callers hang up without leaving a message. Since this is not ascertainable by the user of the answering device, he is forced in every case when the lamp indicating a received call comes on to listen to the recording memory means.
The object of the present invention is to provide a telephone answering device of this type which provides more detailed information on the nature of the calls.
According to the present invention, the telephone answering device comprises recording means for recording calls and incoming messages, a ring detector means producing a start signal for an announcement memory means, voice detector switch means for supplying a start signal to the recording memory means for recording an incoming message, and display means for indicating that a call or calls have been received, the display means including two numeric display means, of which the first indicates the number of calls and the second the number of calls which have been recorded as incoming messages on the recording memory means.
With the construction of the telephone answering device according to the invention the user can immediately determine how many callers have called during the operating time of the telephone answering set and how many of these callers have left a message which has been recorded on the recording memory means. If only calls with which no messages were recorded have been made, the user has no need to listen to the recording memory means. Further, the display of both the calls which have been made and of the calls where a message was left and recorded on the recording memory means provides an indication of the effectiveness of an announcement text and this can be of considerable significance in business.
The two numeric display means are preferably driven by two digit decimal counters which, depending on the signals available in the telephone answering device, count the start signals for the announcement memory means and the start signals for the recording memory means. The start signals are applied either via an evaluating circuit which evaluates only the start signals of the announcement memory means which are followed by a recording of a message of at least a predetermined length, or alternatively, rewind signals of the recording memory means generated in the answering device are used for decrementing the counter for the recorded calls if, in the answering device, provision is made for the recording memory means to be rewound when no message is spoken by the caller after the start signal of the recording memory means.
The output singals of the counter stages of the two counters are preferably supplied via multiplexers and associated decoders to a four-digit digital display. Provision is preferably made for the counters, the multiplexers, the decoders and a clock pulse source or a clock pulse evaluating circuit to be combined with the digital display to form a single constructional unit or a module which can be inserted as a finished unit into the answering device.
For a better understanding of the present invention, reference may be had to the accompanying drawing wherein a block circuit diagram of an embodiment of the display means of a telephone answering device is illustrated.
For further details of a known telephone answering set in which the display means according to the invention can be used, attention is drawn to already mentioned U.S. Pat. No. 3,937,893. Such a telephone answering device comprises a ring detector which detects an incoming call and furnishes a start signal to an announcement memory, for example a cassette drive, which plays back a previously recorded announcement text to the caller. Such a telephone answering set further comprises a voice detector switch which monitors an incoming call to determine whether after the end of the announcement text a message is spoken by a caller and is to be recorded by the recording memory. This voice detector switch accordingly supplies a start signal to the recording memory. If within a predetermined time after the end of the announcement text no message is spoken by the caller the recording memory is stopped and possibly rewound to the respective start point. In the latter case, a rewind signal is furnished to the recording memory.